52 DIPLODIA CORCHORI SYD. 
temperature of 68°F., and that the range of infection of bean (Phaseolus vulgaris) 
with Colletotrichum Lindemuthianum (Sace. et Magn.) Biv. & Cav. lies between 
92 per cent. and 100 per cent. at a temperature of 68°F. In the case of buck 
wheat (Fagopyrum esculentum Mecench.) with Asochyta Fagopyrum the range 
of infection at 77°F. lies between 90 per cent. and 100 per cent. 
The fact that late sown jute, and generally the smaller stems, escape the 
disease has been frequently mentioned and suggests a method of raising a clean seed 
crop. Of the cause of this relative immunity in late sown jute little can be said 
at present ; that the immunity of late sown jute is not absolute is shown by the 
successful infections in Experiment XVIII. It is noteworthy that when from some 
local richness of soil late sown plants attain a large size they are frequently 
attacked by the disease. This suggests that the relative immunity of smaller stems 
may perhaps be due to some anatomical difference in the external layers which 
renders the smaller stems less liable to penetration by the germ tube of the fungus, 
or more probably that the development of a large stem is connected with some 
physiological condition which renders it a more favourable medium for the parasite. 
Other cases in which the host plant is more susceptible to the attack of a parasite 
when in the mature condition are not unknown. The susceptibility of shaftal 
(Trifolium resupinatum) to the attack of Polythrincium Trifolii in the Peshawar 
District being a case within the writer’s experience. Chemical investigations are 
in progress on the composition of jute stems from late and early sown crops but 
are not, at present, sufficiently advanced to admit of any discussion. There is a 
suggestion, in the results obtained up to date, that the stems of late sown jute are 
richer in soda (Na2Q) and sulphuric acid (SO4) than those of the early sown crop. 
Field Experiments. 
During the process of threshing out jute seed it was obvious that a large 
number of spores of D. Corchort would become mixed with the seed and might serve 
to disseminate the disease in the next season’s crop. Microscopic examination of 
samples of jute seed from a badly diseased crop showed the presence of Diplodia 
spores among the seed; the fact, however, that D. Corchori was already present 
in the jute-growing districts suggested that the presence of spores mingled with 
the seed would not prove a very potent factor in increasing the amount of disease. 
As, however, the Bihar seed crop was to be distributed throughout the jute-growing 
districts of Bengal in small packets, it was considered advisable to disinfect the seed, 
pending the results of experiments designed to show whether seed disinfection had 
any influence in lessening the incidence of the parasite. Experiments showed that 
jute seed could be steeped for 10 minutes in a 2 per cent. solution of copper sulphate 
and thoroughly dried without injury to germination, and that this treatment would 
